JP4846172B2 - Flexible stent - Google Patents

Abstract

A preferred embodiment of a stent provides a folded strut section (20) that provides both structural rigidity and reduction in foreshortening of the stent mechanism. A flexible section (30) provides flexibility for delivery of the stent mechanism. In a second embodiment, flexible section columns (130) are angled with respect to each other, and to the longitudinal axis of the stent. These relatively flexible sections are oppositely phased in order to negate any torsion along their length. In yet another embodiment, the flexible connector (310) can take on an undulating shape (like an "N"), but such that the longitudinal axis of the connector is not parallel with the longitudinal axis of the stent. Finally, a new method is disclosed for making stents. The method consists of performing a standard photochemical machining process of cutting, cleaning and coating the tube with a photoresist. However, unlike former methods, the photoresist image is developed on the surface of the cylindrical metallic tube, which results in a controlled variable etching rate at selected sites on the cylindrical metallic tube during the etching process. Further embodiments provide living hinge connectors (330) and connections along the length of the radial strut member.

Description

[0001]
BACKGROUND OF THE INVENTION
Stents are commonly known as tubular structures that are left in the lumen of a duct to reduce occlusion. Generally, a stent expands autonomously (or with a second aid) in situ after being inserted into the lumen in an unexpanded form. A typical method of dilation is through the use of an angioplasty balloon attached to a catheter, which is inflated in a stenotic vessel or body passage and attached to a wall component in the vessel. The occluded part is sheared and collapsed to form an expanded lumen.
[0002]
[Prior art]
In the absence of a stent, restenosis occurs as a result of elastic recoil of the stenotic lesion. To date, a number of stent designs have been reported, but these designs have the disadvantages of a number of limitations. These limitations include limitations on the dimensions of the stent.
[0003]
Another stent has been reported as a stent composed of a plurality of cylindrical components that are flexible in the longitudinal direction and connected together. Such a design, for example, results in a protruding edge portion when the stent is bent along a curved portion, and the stent is accidentally retained on plaque deposited on the arterial wall. It has at least one important disadvantage that arises. This can also cause the stent to become embolized or misaligned, further damaging the inside of a healthy vessel.
[0004]
Thus, stents are known in the art. Such stents can be expanded during or immediately after balloon angioplasty. As a general rule, stent manufacturers need to compromise on axial flexibility to allow for the expansion described above and to achieve overall structural integrity.
[0005]
A conventional stent has a first end and a second end with an intermediate portion between the two ends. Such a stent further has a longitudinal axis and comprises a plurality of longitudinally disposed zone portions, each zone portion being generally continuous along a linear portion parallel to the longitudinal axis. A wavy structure. Further, a plurality of connecting members maintain each band in a constant tubular structure. In another embodiment of the present invention, each band portion arranged in the longitudinal direction of the stent is connected to an adjacent band portion by a connecting member along a short outer circumferential direction at a plurality of periodic positions. . The wavy structure with each of these band portions has substantially the same frequency as the basic three-dimensional frequency in the middle portion, and each band portion has a three-dimensional portion of each wavy structure associated with it. Are arranged so as to have substantially the same phase. Each of the three-dimensionally aligned band portions is connected to the adjacent band portions by connecting members along the short outer peripheral direction at a plurality of periodic positions.
[0006]
In particular, at each one position in the first group of common axial positions, there is a connecting member along the outer circumferential direction between each pair in the first set of adjacent band portion pairs. Yes.
[0007]
Further, at each one position in the second group of common axial positions, there is a connecting member along the outer circumferential direction between each row in the second set of adjacent band portion rows. And along the longitudinal axis, a certain common axial position is alternately generated in the first group and the second group, and the first group and the second group are arbitrary. Are selected to be connected to adjacent band portions in only one of the first group and the second group at the common axial position.
[0008]
Furthermore, the stent described above is uniform throughout, but can be modified to provide a bifurcated approach. If the manufacturer designs such a stent to have a certain sufficiently large opening, place the stent in such a way that a pair of stents can be placed with one inserted into the other. Is possible. In such a manner, these stents can be placed at the bifurcation without any welding process or any special attachment. Also, an interlock mechanism can be incorporated into the stent design described above, resulting in a stent design that interlocks the stent at a desired location during device assembly.
[0009]
In addition, metallic stents have been designed that include repeated closed loop shaped portions. This stent is designed so that the closed loop does not change dimensions during expansion. Such composite stents are formed by filling the area surrounded by each loop with a material that enhances the clinical performance of the stent. This material can be ceramic or polymer and can be permanent (usable) or absorbable and porous or non-porous, such as: therapeutic agents, radiopaque dyes, radioactive Contain one or more materials capable of releasing a therapeutic agent, including any material or combination of rapamycin, cladribine, heparin, nitrous oxide or any other known drug it can.
[0010]
[Problems to be solved by the invention]
To date, however, it is desirable to provide a stent that has both the flexibility to pass through tortuous lesions and the increased strut strength to maintain the necessary stiffness after installation in a body lumen. I know that. Such preferred designs tend to provide flexibility due to the undulation of the longitudinal connecting members. Rigidity is also largely provided by a slotted tubular stent mechanism. It is further believed that there may be mechanisms that can enhance the properties of these types of stents. Such stents are flexible when delivered and exhibit rigidity when installed.
[0011]
It is further desirable to be able to produce a stent where the cross-sectional shape of either the strut portion or the connecting member is a tapered (or variable) dimension. In addition, it may be desirable to modify the stent to have a non-rectangular cross section. It should be noted that in both cases, different manufacturing methods can assist in the formation of such a stent.
[0012]
[Means for Solving the Problems]
An object of the present invention is to provide a stent having relatively few shortened portions.
[0013]
The object of the present invention is to provide a stent with a certain increased degree of flexibility.
[0014]
It is to provide a stent as described above while reducing any cause that compromises the structural rigidity of the stent upon expansion.
[0015]
Another object of the present invention is to provide a novel method for manufacturing stents.
[0016]
  These and other objects of the present invention are described in the following description. As described herein, a preferred embodiment of a stent is a flexible portion and a fold.FoldingAn apparatus is provided that includes a state strut portion. This foldFoldingThe column part in the state opens when expanded (like a flower). This foldFoldingThe state strut portion provides both structural rigidity and reduced shortening in the stent mechanism. The flexible portion also provides flexibility for delivery of the stent mechanism.
[0017]
In a second embodiment of the device, a cylindrical part and a flexible part are present. This cylindrical portion provides a device that extends longitudinally when expanded. The flexible portion also provides a portion that shortens somewhat in the longitudinal direction when expanded. This results in no stent shortening or stretching during expansion. One of the cylinders of the flexible portion is inclined with respect to the other, and is also inclined with respect to the longitudinal axis of the stent to provide flexibility during delivery. In addition, this configuration adds additional resistance to the balloon to prevent “dogboning” of the stent on the balloon during delivery and slipping of the balloon along the stent. These relatively flexible portions are placed in a phase state opposite to each other to counteract any twist along their respective lengths. In addition, these flexible portions can be crimped onto the balloon catheter in a generally smaller shape than conventional stents to increase the retention of the stent on the balloon.
[0018]
In yet another embodiment of the stent of the present invention, the flexible connecting member may take a corrugated shape (such as an “N” shape) but is not parallel to the longitudinal axis of the stent. In such a manner, the flexibility is adjusted in a predetermined axis that is different from the longitudinal axis of the stent. Such a configuration is desirable when it is selected to place a stent within a particular form of vessel that is predetermined by known means such as, for example, an intravascular ultrasound device (“IVUS”).
[0019]
In yet another embodiment of the present invention, a “living hinge” type connection member is provided, which generally turns a flexible connection member into a relatively strong radial strut member. Connecting. These integral hinges achieve a number of identical characteristics found in the embodiments described hereinbefore disclosed herein. First, because these integral hinges tend to expand upon expansion, the shortening of the stent length is further reduced. Second, there is a certain combined radial strength supplied at the intersection between these integral hinges and the radial strut members. This creates a small “hoop” that further resists kinking or collapse in situ. Third, as a natural consequence of the second property, each of the integral hinge connecting members provides a reduced strain along the equivalent length of the stent.
[0020]
In yet another preferred embodiment of the stent of the present invention, the connection point between the radial member and the connecting member moves to a fixed position along the length of the radial strut portion. In general, this connection point can be located at any intermediate position along the length of the column portion. By moving this elastic connection point closer to the middle position of the radial annular member, the shortening can be addressed in a coordinated manner. In fact, apart from the balloon interaction, the connecting member need not extend to compensate for the shortening. When these stretchable connecting members are connected to the midpoints of the radial annular members, the distance / length of the intermediate portion of the stent between the radial annular members remains unchanged. This is because the intermediate point is maintained at a relatively same position in a state in which the arc-shaped portion in the radial direction of each column portion moves from both sides to approach the intermediate point. Furthermore, by moving the attachment position of this stretchable connecting member from the middle point of the column part to the opposite side, it is possible to actually use the column part that is moving closer to this middle point. Thus, the stent at the time of expansion can be expanded.
[0021]
In addition, in this embodiment, each adjacent radial annular member starts from a different phase in the unexpanded state. Thereafter, during expansion, each radial ring member tends to align itself (in the same phase) due to the diagonal orientation of the connection points in each flexible connection member. As a result, a more uniform and constant space portion is formed, and an improved support structure of the vessel can be formed. Furthermore, a “wavy” strut structure is described, which allows a flexible connecting member at or near the strut midpoint in order for the strut portion itself to partially contribute to the expansion described above. Both reduced crimp shape for mounting and reduced strain on expansion can be promoted.
[0022]
Furthermore, a novel method for making a stent is disclosed. In this way, a novel photochemical processing of cylindrical tube material is provided. This method consists of performing standard photochemical processing including cutting, cleaning and coating the tube with photoresist. However, unlike the conventional method, the photoresist image is developed on the surface of the cylindrical metal tube material, and this method allows each of the predetermined images on the cylindrical metal tube material during the etching process. A controlled and variable etching rate of the part can be realized. The photoresist image is made up of a series of circular regions having various diameters that are formed at various distances along the stent. As the diameter of the circular photoresist pattern decreases, the distance between the circular photoresist patterns along the stent increases and the etch rate of the device also increases. Such a change in the photoresist pattern causes a change in the amount of metal that is removed during the etching process.
[0023]
The above method can be used to locally change the shape of the cylindrical and metallic tube material. An advantage seen with this method is the ability to produce a tapered strut portion along the stent. Furthermore, post portions having a cylindrical or other non-rectangular cross-section can be manufactured. In addition, each surface feature can be positioned, for example, to provide a storage location that is positioned within the stent to deliver the drug.
[0024]
These and other objects of the present invention will become apparent from the following accompanying drawings and detailed description of the invention.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
  As can be seen in FIG. 1, a series of folds connected by a series of flexible portions 30.FoldingA cylindrical stent 10 is shown having a strut portion 20 in a state. FoldFoldingEach column portion 20 in the state has a pair of ends 24, 26 and is generally folded.FoldingThe column member 25 in a state is provided. Each pair of these ends 24, 26 is a separate foldFoldingIt is also connected to the ends of the column member 25 and the flexible member 35 in the state. Thus, each end 34, 36 of one flexible member 35 is folded one.FoldingThey are connected to the two end portions 24 and 26 of the column member 25 in the state.
[0026]
  FoldFoldingEach strut member 25 in the state has a generally irregular pattern. On the other hand, each flexible member 35 has a generally wavy pattern. Fold aboveFoldingEach strut portion 20 in the state wraps around the cylindrical outer periphery of the stent 10. Each flexible portion 30 is also folded along the outer periphery of the stent 10.FoldingIt is connected to the column part 20 in the state. In this case, it can be seen that the adjacent flexible portions 30 are arranged 180 degrees out of phase with each other.
[0027]
  FoldFoldingThe length of each strut portion 20 in the longitudinal direction is sufficiently short to form a smooth outer shape when the stent 10 is bent. Also this foldFoldingThe column portion 20 in the state can be expanded in a large diameter direction at the time of expansion. Therefore, when expanding,FoldingEach strut portion 20 in the state expands in the outer circumferential direction to form a hoop shape, and maximum radial strength is achieved. Meanwhile, theseFoldingEach flexible portion 30 disposed between the state strut portions improves stent delivery in the unexpanded dimensions of the stent 10. These flexible portions 30 are flexible in the longitudinal direction, and shortening during expansion can be minimized.
[0028]
Thus, in use, the stent 10 of the present invention is placed on a balloon catheter and travels in a snake-like manner within a vessel and placed within a artery, typically a lesion site within a coronary artery. The The flexible portion 30 is substantially flexible so that it can pass through a tortuous lesion portion relatively easily. Once deployed, the balloon catheter is expanded by conventional means. At the time of expansion, each column member 25 in the column part 20 is expanded to obtain a hoop-like shape. In addition, since these members expand in the longitudinal direction, the reduction in size is reduced. Of course, since the flexible member 35 becomes linear at the time of expansion, the stent can further provide strength in a linear and rigid state.
[0029]
  Variations of the present invention can be seen in the stent 50 in FIG. 2 (“angled version”) and FIG. 3 (“straight version”). In these examples, each strength portion 120 in the radial direction is achieved by each member 115 being generally linear, but these members are folded.FoldingIt does not have a state column part. In addition, the connection structure between the substantially linear members 115 is very similar to the connection structure formed in relation to the connection members of the first embodiment in FIG. It is formed by connecting the member 115 to the flexible member 125 respectively.
[0030]
The members for reducing the shortening are the respective inclined members 130, which are shown 180 degrees out of phase with each other. The connection structure between each of these flexible members 130 is formed at the end of one particular relatively inflexible member and the tip of one particular inclined member 130. Yes. Next, when the column portion constituted by the relatively rigid member 115 is expanded, the length of each flexible member 130 is shortened. However, the longitudinal length of each of these inclined members 130 is oriented at a constant angle with respect to the longitudinal axis of the stent 50. Therefore, when expanded, each of these inclined members 130 actually extends relative to the longitudinal axis of the stent 50. Thus, as a result of these overall, no shortening occurs when the stent 50 is expanded.
[0031]
  Each of the tilted members 130 is tilted for the purposes of both increasing flexibility and applying additional resistance on the balloon surface. Such a configuration helps prevent exposure of any leading edge portion of the strut member 75 contained at either end of the stent 50, known as "dogboning". To do. In addition, this configuration prevents slippage along the balloon surface of the stent. Each of the tilted members 130 is tilted in opposite phases (ie, having a 180 ° phase change) to counteract any twisting effects in each strut portion 75, 85 along the length of the stent. Each of these specific members can be crimped to a lower profile than the more rigid members to ensure increased retention of the stent on the balloon catheter surface. Furthermore, this configuration described herein is specifically folded.TatamiAnd can reduce the risk of “flaring” of the edge portion of each strut portion 75, 85 during movement in the lumen.
[0032]
When a relatively small outer shape is desired, the position (“order”) in the longitudinal direction of each column portion can be changed. That is, if it is desired that the outer shape be relatively small, the relatively rigid portions 120 (or portions thereof) can be removed and replaced with generally inclined portions 130.
[0033]
Moreover, it turns out that the amplitude of the wave of each support | pillar member in a specific support | pillar part is not maintained constant. The amplitude of the wave, which is defined as “W” in the specification, can be increased if possible due to its shape. For example, note the space portion S formed between one set of strut members A and a second set of strut members B. Such a particular configuration allows a certain increased extent of expansion around the unexpanded outer periphery of the stent and is suitable for the metal strut portion disposed around the outer periphery of the stent. Extended area is maintained. Such optimization of the surface area of the strut portion is important in that an appropriate covering of the lesion portion can be ensured by expanding the stent.
[0034]
The stent 50 of the particular embodiment described above is expanded in much the same way as the stent 10 of FIG. That is, when expansion is caused by the balloon catheter, the angled member 130 extends to prevent shortening of the stent 50, and the relatively rigid member 120 shortens in the longitudinal direction to provide a fully expanded stent. Relatively large rigidity. However, it will be understood that in the expansion of both stents 10, 50 described above, the ability to flexibly maneuver the vessel is enhanced by the configuration of either stent 10, 50, as the case may be. In all conditions, the tendency to shorten the stent during expansion is greatly reduced.
[0035]
As can be seen in FIG. 4, a stent 175 may also be provided that does not include an inclined portion. However, the stent 175 expands with a shortening that is reduced along its length due to the unique shape of the stent 175. In this case, each stent strut portion 180, 190 provides a relatively constant length along its longitudinal axis. (In other words, the longitudinal dimension of each post portion 180, 190 in the combined state is maintained relatively constant in either the expanded state or the unexpanded state.) The stent 175 maintains a generally constant length in any of its expanded state, unexpanded state, or partially expanded state.
[0036]
4 and 5 show another embodiment of a similar stent 200 design. In this case, the connecting member 250 has an “N” shape, and the “N” shape in the Bx Velocity® stent sold by Cordis Corporation of Miami Lake, Florida, found on the market. This connecting member was filed on November 13, 2000, which is hereby incorporated by reference and assigned to Cordis Corporation, and is now a U.S. Pat. No. 6,190,403B1, US patent application Ser. No. 09 / 192,101, and US patent application Ser. No. 09 / 636,071 filed Aug. 10, 2000, at least in part. It is disclosed.
[0037]
In the stent 200, as best shown in FIG. 4, the relatively rigid portion R includes strut portions 210, 220 that are not equal in length a, b. Further, as can be seen in FIG. 5, the pattern of the column portion is formed so that each joint point at the end of each flexible connecting member 250 can be arranged at any point along each column portion 210, 220. . In such a manner, when the stent is expanded, the relatively stiff portion R "holds" the connecting member 250 along the surface of the lesion portion, so that the tensile strength of the stent and its associated Both support is maintained to a high degree at each site of the lesion. However, in the unexpanded configuration, each of the “N” shaped flexible connecting members 250 can guide the stent 200 along almost any tortuous vessel bend including the tortuous coronary artery.
[0038]
As can be seen from FIGS. 4 and 5, the stent 200 of another embodiment described above can also reduce shortening along its entire length. The stent includes a relatively rigid portion R that includes a relatively rigid portion R and a connecting member 250. (Each flexible portion F is in the form of a connecting member 250 along the wave-like longitudinal direction.) Also, each relatively synthetic portion R is generally formed by strut portions 210 and 220 around the slot S, respectively. Including a slot-shaped configuration. These relatively rigid portions R include the strut portions 210, 220 in the combined state as described above, and the strut portions 210, 220 each have a different longitudinal length.
[0039]
As can be seen from each of the above drawings, each column portion 210 is formed relatively long at a position along a part of the radial direction. Each strut portion 220 is made relatively short at a position along another radial direction. However, these relatively short strut portions 220 have a constant length b in a manner that connects to each relatively flexible connecting member 250 along the longitudinal direction. Also, as described above, each relatively rigid portion R is relatively flexible due to the frictional force maintained by these relatively rigid portions R in the balloon portion of an angioplasty balloon catheter. Each portion F is maintained at a substantially constant longitudinal length. Thus, when expanded, the constant length b, together with the generally constant length of the relatively flexible connecting member 250, causes the stent 200 to have a relatively constant longitudinal length at any diameter that the stent 200 expands. Maintain directional dimension L. Also, as will be appreciated, maintaining this constant length is desirable in terms of a reliable and repeatable placement of the stent within the vessel.
[0040]
Further, to illustrate the stent 200 of FIGS. 4 and 5, each flexible portion F operates according to the behavior of each flexible connecting member 250 to provide a similar type of “N” shaped flexible connection. Acts in the form of members. That is, since the flexibility of the stent 200 is concentrated in this region F, a relatively narrow lesion portion can be moved by such a form or configuration. In addition, since the relatively high strength portion R can be expanded to a relatively high strength plastically deformed state, the stent 200 can support the artery wall in this manner. Although the longitudinal dimensions of the column portions 210 and 220 in the relatively strong portions R are unequal, such a configuration does not reduce the radial support force in the expanded state. Therefore, it is considered that the stent having such a shape can appropriately support the artery wall at the lesion site and can maintain the radial flexibility and the longitudinal length.
[0041]
As best shown in FIG. 7, yet another embodiment of the present invention will be described. In FIG. 7, a stent 300 is included that resembles Bx Velocity® sold by Cordis Corporation of Miami Lake, Florida. In FIG. 7, the stent 300 also includes a generally flexible connecting member 310 that is connected to a generally rigid radial strut member 320. These connecting members 320 are generally formed in an “N” shape, and each strut 310 is generally formed in a radial fashion around the outer periphery of the stent. The connection between each flexible connecting member 320 and each radial strut member 310 is formed by an integral hinge 330. The integral hinge 330 includes an outer radial arcuate portion 332 and an inner radial arcuate portion 334. In the expanded configuration, these radial arcuate portions 332, 334 move away from each other, and the overall length of the integral hinge 330 actually increases upon expansion.
[0042]
Known conventional means, such as an angioplasty balloon, or a balloon on a stent delivery system expands the stent 300 of the present invention. Upon expansion, a number of advantages are gained by the stent 300 of the present invention. First, when expanded as described above, the shortening of the stent 300 is reduced because the outer radial arcuate portion 332 does not actually shorten. That is, the arcuate portion 332 extends slightly so that the overall length of the stent 300 is maintained at its generally nominal length. Also, each arcuate portion 332, 334 in the radial direction is flexible and in a respective connection portion between each strut portion 320, 310 in the radial direction (both these inner and outer radial arcuate portions 334, 332 ) To provide superior strength at the site of these arcuate portions, resulting in increased radial strength, and since the radial strut portions 310 are parallel to the loading direction on the stent 300, optimal radial strength is achieved. In order to provide a constant “hoop” at the outer peripheral portion C of the stent. Also, since each of the radial arcuate portions can accept a relatively large force, strain corresponding to an equivalent strength designed for the stent is reduced. In all, the stent 300 of the above embodiment exhibits at least equivalent radial strength, reduced shortening and reduced strain when compared to current stents.
[0043]
Next, as can be seen from FIGS. 8, 9 and 10, yet another embodiment of a stent 400 in accordance with the present invention is shown. Again, the stent 400 includes a generally relatively strong radial portion R that includes strut portions 410 along the radial direction, the strut portions 410 generally extending around the circumference of the stent. It is in the state of a slot that is changing alternately. The flexible connecting member 420 is similar to the flexible connecting member shown in FIG. 7 and is also similar to the flexible connecting member in the Bx Velocity® stent described above. However, these flexible connecting members 420 are connected to each of the radial strut portions at a location that is approximately near the midpoint of each radial strut portion 410. In this manner, upon expansion, the lengths of these connecting members 420 are maintained regardless of the shortening or extension of each strut portion 410 in the radial direction. Furthermore, in this way, the overall length of the stent is maintained, as can be seen from the schematics in FIGS.
[0044]
Due to the overall ability to maintain the length of the stent 400 as described above, the radial strut portion 410 only provides radial strength and does not contribute to shortening the stent in one or another direction. Also, each strut portion 410 in the radial direction is generally formed in a “wavy” pattern. This wavy pattern is useful in assisting in reducing the crimped profile of the stent 400 on the balloon. This effect is obtained by a relatively smooth attachment of each strut portion 410 in the radial direction to each flexible connection portion 420. Furthermore, by forming such a configuration, it is possible to reduce the distortion generated in each column portion 420 during expansion. Such reduced strain can be achieved by the location of connection of each connecting member 420 to each strut portion 410. Since there is relatively little movement of each post portion 420 in the longitudinal direction, there is relatively little distortion that occurs in these post portions during expansion. Also, the radial arcuate portion 415 in each strut portion 410 can be ideally placed in a “shifted” configuration to further facilitate crimping on the stent balloon.
[0045]
Further, according to FIG. 8, the radial strut members 410 are attached to the flexible connecting members 420, and the flexible connecting members 420 are approximately “spiral” around the length of the stent 400. It can be seen that it proceeds along the “spiral” pattern S. Each connection point 422 in each flexible connection member 420 is arranged in an orthogonal manner in each post portion 410 to increase flexibility. In general, each connection point 422 is located at an intermediate point of the post portion 410. Further, when these connection points 422 are positioned past the strut portion 410 (ie, at a location far from the midpoint of the strut portion 410 and offset from the direction of the connection member 420), the nominal stent strength is as described above. Naturally increases on expansion when compared to a stent. Such a configuration reduces the shortening as described above. In addition, this configuration has no twisting effect on the stent when it is delivered to the lumen by a balloon catheter. Balloon friction against each strut portion 410 also maintains these strut portions 410 (and their respective strut portions 420) in generally the same radial position during expansion. By reducing any involvement of stent twist, the overall slippage of the balloon is also reduced. The connecting members 420 are not aligned with each other, but they are maintained in their respective positions on the surface of the balloon. Upon expansion, when the stent 400 is deployed, each strut portion 420 is secured to increase strength within its lumen.
[0046]
8 and 9, the inventor finds that the connecting member 420 is important for maintaining the length. That is, on the connection side between the strut portions 410 and 420, the greater the distance from the connection member 420 to the intermediate point M, the greater the potential for shortening the stent. This creates a need to eliminate any shortening by other means in the absence of the solution described herein.
[0047]
It will be understood that various modifications can be made to the stent 400 of FIGS. 8, 9 and 10 without departing from the invention described herein. For example, the connection member 420 described above is intermittently disposed around the outer periphery of the stent 400 and may not be disposed with respect to all of the radial strut portions 410. Also, each strut portion 410 in the radial direction is out of phase by approximately 90 ° between each strut portion 410a and the next strut portion 410b, but these are shifted by 30 ° to 150 °. Can also be expected. Also, in this arrangement, the strut portion 410 is “encouraged” to bend in a particular manner, which may be preferred in the design of a stent with a particular purpose. .
[0048]
Each of the above stents can be manufactured by known conventional means such as laser etching, electrical discharge machining (EDM), photochemical etching and the like. However, the present invention described herein also discloses a novel method of performing a photochemical resistance etching process on a tube for making a stent. This novel method allows for the manufacture of stents having a variable shape in three dimensions, ie, along their length, direction across the circumference, and along their depth (or radial direction). This method begins with standard photochemical processing.
[0049]
The above-described novel method includes a stent cutting step by photochemical etching, a stent cleaning step, and a subsequent step of coating the stent with a photoresist. This photoresist coating is provided in a circular shaped portion 290, as can be seen in FIG. These shaped portions 290 are intentionally shaped to change the size of their respective radii. A photoresist image is then developed on the surface of the cylindrical metal tube T that initiates the stent. The photoresist image is developed in a controlled manner by known means. Development of the photoresist in this manner allows for a controlled and variable etch rate at each predetermined location along the cylindrical metal tube.
[0050]
As already mentioned, a new photoresist image can be seen in FIG. The photoresist image is made up of a series of circular regions of photoresist material 310 that are shaped at variable diameters desired in manufacturing. The photoresist images 310 are arranged at a variable distance D from each other. As the diameter of this circular photoresist pattern 310 decreases and its distance from another photoresist pattern 310 increases, the etch rate of this region increases. Thus, by intentionally placing such a photoresist pattern 310 on the stent, any variable dimension can be created in any direction along the stent.
[0051]
By varying the photoresist pattern 310, the amount of stent metal removed during the etching process can be varied. This method can be used to locally change the shape of the metal tube.
[0052]
In the above manner, it can be envisaged to create a stent with variable circumferential width, radial depth or longitudinal length. Thus, different flexibility as well as different strengths can be provided along the length of the stent, allowing the stent to be configured for placement at various locations within the body.
[0053]
  Embodiments of the present invention are as follows.
  (A) In a stent having a generally tubular shape and a longitudinal axis,
A plurality of cylindrical portions and a plurality of flexible portions, wherein each of the portions is arranged around an outer periphery of the generally tubular shape, and each one of the cylindrical portions is the flexible portion. Each of the cylindrical portions and the flexible portions of each of the portions when expanded from a first unexpanded configuration to a second expanded configuration. A stent that maintains its longitudinal length.
  (1) The continuous flexible portions are out of phase with each other.Embodiment (A)The stent according to 1.
  (2) Each portion of the flexibility has a fixed axis that is not parallel to the longitudinal axis of the stent.Embodiment (A)The stent according to 1.
  (3) The stent according to embodiment (2), wherein the continuous portions of the flexibility are out of phase with each other.
  (4) The stent according to the embodiment (2), in which the flexible portions are connected to the cylindrical portions by a connecting member, and the connecting members are out of phase with each other.
  (5) Each portion of the flexibility has a constant axis parallel to the longitudinal axis of the stent.Embodiment (A)The stent according to 1.
[0054]
  (6) The stent according to embodiment (5), wherein the continuous portions of flexibility are out of phase with each other.
  (7) The stent according to the embodiment (5), wherein the flexible portions are connected to the cylindrical portions by a connecting member, and the connecting members are out of phase with each other.
  (8) The flexible portions are connected to the cylindrical portions by connecting members, and the connecting members are out of phase with each other.Embodiment (A)The stent according to 1.
[0055]
【The invention's effect】
Accordingly, the present invention provides a stent having relatively few shortened portions, a stent having a certain degree of increased flexibility, and a stent that can reduce any cause of loss of the structural rigidity of the stent when expanded. In addition, novel methods for manufacturing these stents can be provided.
[Brief description of the drawings]
FIG. 1 is a plan view of a stent embodying the present invention.
FIG. 2 is a plan view of another embodiment of the present invention.
FIG. 3 is a plan view of another embodiment of the present invention.
FIG. 4 is a plan view of yet another embodiment of the stent of the present invention.
5 is an enlarged view of the same cross section in FIG. 4 along the line bb in FIG. 4;
FIG. 6 is a schematic view of a photoresist pattern formed on a stent to perform the method for making a stent described in the present invention.
FIG. 7 is a plan view of still another embodiment of the present invention.
FIG. 8 is a plan view of still another embodiment of the present invention.
9 is a schematic view of theoretical posterior expansion of the stent of FIG. 8. FIG.
10 is a schematic view of the theoretical posterior expansion of the stent of FIG. 8. FIG.
[Explanation of symbols]
10 Cylindrical stent
20 Prop part
30 Flexible part
24, 26 A pair of end portions in the column member
25 Prop member
34, 36 Ends of flexible member
35 Flexible members

Claims (2)

In a stent having a generally tubular shape and a longitudinal axis,
A plurality of cylindrical areas, each cylindrical area comprising a plurality of generally folded strut members, and a plurality of flexible areas, each flexible area Comprises a flexible region comprising a plurality of generally folded flexible members;
Each of the zones is arranged along a circumference of the generally tubular shape, and each one of the cylindrical zones is attached to at least one of the flexible zones, the longitudinal direction of the stent; A flexible region is between two adjacent cylindrical regions, and when viewed in the longitudinal direction, the flexible member in a generally folded state of one flexible region is: Inclined to the opposite phase relative to the generally folded flexible member of the adjacent flexible area;
The first embodiment of the unexpanded stent upon expansion of the form of the second expanded state, each zone of the flexibility, and even stretched due to the inclined with shortened in the longitudinal direction, the entire stent The longitudinal length is maintained,
Stent. The stent according to claim 1 , wherein the flexible region is connected to the cylindrical region by a connecting member, and when the connecting member is viewed in the longitudinal direction, one cylindrical region or A stent that is oppositely out of phase with respect to adjacent connecting members across a flexible region.

Images